Preparation of cationic surfactants

ABSTRACT

Compositions that include cationic surfactants and methods of synthesizing compositions that include cationic surfactants. The surfactants include a quaternary amine and a saturated or unsaturated alkyl chain with 4 to 28 carbons. The surfactants can be generated by reacting a fatty acid modified with an amino alkyl group and an epihalohydrin in the presence of a base. The cationic surfactants can be generated by reacting a fatty acid modified with an amino alkyl group, an epihalohydrin, and a carboxylic acid. The cationic surfactants can be generated by reacting a carboxylic acid, an epihalohydrin, and a catalyst to afford a halo-substituted alkyl ester, followed by reacting the halo-substituted alky ester with a fatty acid modified with an amino alkyl group.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims the benefit of priorityto U.S. patent application Ser. No. 16/942,565 filed on Jul. 29, 2020,the entire contents of which are incorporated by reference in itsentirety.

TECHNICAL FIELD

This document relates to cationic surfactants and methods of preparationof cationic surfactants.

BACKGROUND

Surfactants are useful in many household and commercial applications.For example, new surfactants that are soluble and stable under harshconditions would be useful in oil and gas recovery.

SUMMARY

This disclosure describes cationic surfactants composed of erucylamidopropyl groups, with different head groups introduced by reactionwith an epihalohydrin. This disclosure also describes one- and two-stepmethods of producing the cationic surfactants.

In some implementations, a composition includes a compound of Formula I:

where X is halide, Ri is a saturated or unsaturated alkyl with 4 to 28carbons, R₂ is alkyl, R₃ is methyl, and R₄ is selected from the groupconsisting of

In some implementations, a composition includes a compound of FormulaII:

where R is selected from the group consisting of:

and where X is halide.

In some implementations, a process includes reacting a fatty acidmodified with an amino alkyl group and an epihalohydrin, the presence ofa base, to afford a cationic surfactant.

In some implementations, a process includes reacting a fatty acidmodified with an amino alkyl group, an epihalohydrin, and a carboxylicacid to afford a cationic surfactant.

In some implementations, a process includes reacting a carboxylic acid,an epihalohydrin, and a catalyst to afford a halo-substituted alkylester. The process includes reacting the halo-substituted alkyl esterwith a fatty acid modified with an amino alkyl group to afford acationic surfactant. The details of one or more implementations of thedisclosure are set forth in the accompanying drawings and thedescription that follows. Other features, objects, and advantages of thedisclosure will be apparent from the description and drawings, and fromthe claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows an example structure of a cationic surfactant.

FIG. 2 is a flow chart of an example method for the quaternization of atertiary amine.

FIG. 3 is an example reaction of N,N-dimethyl-erucyl-1,3-propylenediamine with epichlorohydrin.

FIG. 4 is a flow chart of an example method of a two-step synthesis ofcationic surfactants.

FIG. 5A is an example reaction of a carboxylic acid and epichlorohydrin,catalyzed by tetrabutylammonium bromide.

FIG. 5B is an example reaction ofN,N-dimethyl-erucyl-1,3,-propylenediamine with the chloro-hydroxyl alkylester synthesized in FIG. 5A.

FIG. 6 is a flow chart of an example method of a one-step synthesis ofcationic surfactants.

FIG. 7 is an example reaction ofN,N-dimethylerucyl-1,3,-propylenediamine, a carboxylic acid, andepichlorohydrin.

FIG. 8 is an example IR spectrum of erucylamidopropyl-2,3-dihydroxypropyl ammonium chloride.

FIG. 9 is an example ¹HNMR spectrum of erucylamidopropyl-2,3-dihydroxypropyl ammonium chloride.

FIG. 10 is an example IR spectrum of erucylamidopropyl-2-hydroxy-3-acetoxypropyl ammonium chloride.

FIG. 11 is an example ¹HNMR spectrum of erucylamidopropyl-2-hydroxy-3-acetoxypropyl ammonium chloride.

FIG. 12 is an example IR spectrum of erucyl amidopropyl-2-hydroxy-3-(2,2, 2-trifluoroacetoxy) propyl ammonium chloride.

FIG. 13 is an example ¹HNMR spectrum of erucylamidopropyl-2-hydroxy-3-(2, 2, 2—trifluoroacetoxy) propyl ammoniumchloride.

FIG. 14 is an example IR spectrum of erucylamidopropyl-2-hydroxy-3-propionyloxy propyl ammonium chloride.

FIG. 15 is an example ¹HNMR spectrum of erucylamidopropyl-2-hydroxy-3-propionyloxy propyl ammonium chloride.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Reference will now be made in detail to certain embodiments of thedisclosed subject matter, examples of which are illustrated in part inthe accompanying drawings. While the disclosed subject matter will bedescribed in conjunction with the enumerated claims, it will beunderstood that the exemplified subject matter is not intended to limitthe claims to the disclosed subject matter.

Provided in this disclosure, in part, are cationic surfactants andmethods of producing cationic surfactants. These surfactants are usefulin enhanced oil recovery applications. For example, many carbonatereservoirs have high temperatures and high brine salinity. Currentlyavailable surfactants and polymers have limited utility in these hightemperature, high salinity formations. Accordingly, it is essential todevelop new surfactants that are stable and useful at high temperatureand high salinity situations. In addition, the surfactants withultra-low interfacial tension, for example tension below 10⁻³ mN/m, areuseful for releasing trapped oil in a reservoir. Accordingly, there is aneed for surfactants that are stable at high temperature and highsalinity formations that also display low or ultra-low interfacialtension with brine solutions.

FIG. 1 shows the structure of an example cationic surfactant. In someimplementations, the surfactants include a hydrophobic tail Ra, an alkylspacer where n=1 to 6, and a cationic amine with two methyl groups and afunctional group Rc. The resulting cationic surfactants, described inmore detail below, are stable in high temperature and high salinityenvironments. Accordingly, these surfactants are useful in drilling andoil recovery applications, for example, for chemical flooding in acarbonate wellbore.

In some implementations, the hydrophobic tail Ra is derived from asaturated or unsaturated fatty acid with 4 to 28 carbons. The fatty acidtail can be branched, unbranched, saturated, or unsaturated in either acis- or trans-configuration. The properties of the fatty acid tail caninfluence the properties of the surfactant, for example, by influencingthe melting point, stability, solubility, or the critical micelleconcentration of the surfactants in seawater.

In some implementations, the surfactants include ultra-long fatty acidchains, for example chains of 18 or more carbons. In someimplementations, the fatty tail can be derived from erucic acid, amonounsaturated C_(22:1ω9) fatty acid. Ultra-long fatty acid chains arevery hydrophobic and typically not soluble in high salinityenvironments. However, the cationic surfactants described in thisapplication have low interfacial tension and can be used in highsalinity environments.

In some implementations, the fatty acid head group is modified with analkyl spacer. For example, the carboxylic acid head group of a fattyacid can be reacted with an alkyl amine to form an amide bond between analkyl spacer and a fatty acid. The alkyl spacer can be saturated alkylgroup containing 1 to 6 carbons. For example, the spacer can be a propylgroup. In some implementations, the spacer can include a tertiary aminefunctional group. This tertiary amine can be quaternized. For example,the reaction between a tertiary amine and an epihalohydrin results in aquaternary amine.

Quaternization of the tertiary amine introduces functional group Rc andresults in the cationic surfactant. The positively charged amine of thecationic surfactant influences the solubility and stability of thesurfactants. For example, in high-salinity environments the cation canreduce surfactant adsorption in carbonate reservoirs. The cation canalso improve the stability of the surfactant at high salinityenvironments, for example in brines with high concentrations of divalentions such as Ca²⁺ and Mg²⁺.

Quaternization of the tertiary amine can be achieved by a reaction withan epihalohydrin. For example, epichlorohydrin can quaternized thetertiary amine. Other epihalohydrins can also quaternized the tertiaryamine. This results in an amine functionalized with an epoxy group.Under basic conditions, the epoxy can hydrolyze, yielding a dihydroxyfunctional group.

FIG. 2 shows an example flow chart of a reaction scheme 200 forquaternization of a modified fatty acid. At 202, a fatty acid modifiedwith a tertiary amine is combined with an epihalohydrin in a 1:1 molarratio in a solvent. Suitable epihalohydrins include epichlorohydrin. At204, the mixture is stirred, with heating, for 5-24 hours. At 206, thepH of the mixture is decreased to induce a basic condition. At 208, thesolvent is removed from the mixture. At 210, the product isrecrystallized. At 212, the final product is obtained by filtration.

An example of the reaction scheme 200 is shown in FIG. 3, where N,N-dimethyl-erucyl-1,3-propylenediamine is reacted with epichlorohydrin.This functionalizes the quaternary amine with an epoxide. Under basicconditions, the epoxide can hydrolyze, yielding a 1,2-dihydroxylpropylfunctional group. Recrystallization of the product results in thecationic surfactant erucyl amidopropyl-2,3-dihydroxypropyl ammoniumchloride.

Cationic surfactants can also be synthesized using a two-step process400. FIG. 4 shows an example flow chart of a reaction scheme 400 tosynthesize cationic surfactants. At 402, a carboxylic acid is combinedwith an epihalohydrin at a 1.25:1 to 2:1 molar ratio in the presence ofa catalyst. The choice of carboxylic acid can be used to introduceadditional functional groups, such as hydroxyl, ester, or polymerizablegroups such as a vinyl double bond. At 404, the mixture is stirred withheating for 5-20 hours. At 406, the pH of the mixture is adjusted toapproximately 7. At 408, the mixture is filtered to obtain thehalogenated alkyl ester product. At 410, the halogenated alkyl ester ismixed with a modified fatty acid that contains a tertiary amine. At 412,the mixture is refluxed for 5-24 hours. At 414, the solvent is removed.At 416, the product is recrystallized. At 418, the final product, thecationic surfactant, is obtained by filtering.

FIG. 5A shows an example reaction of the first step of the two-stepprocess 400 between a carboxylic acid (COOR) and epichlorohydrin,catalyzed by tetrabutylammonium bromide (TBAB). Suitable carboxylicacids include, but are not limited to, acetic acid (R=—CH₃),trifluoroacetic acid (R=—CF₃), and propionic acid (R═—CH₂—CH₃). FIG. 5Bshows an example reaction of the second step of the two-step process400, where N,N-dimethyl-erucyl-1,3,-propylenediamine is combined withthe chloro-hydroxyl alkyl ester synthesized in FIG. 5A. This generates acationic surfactant that is compatible with brine solutions and has lowoil-brine interfacial tension.

In some implementations, the cationic surfactants can be synthesizedusing a one-step process. In the one-step process, a carboxylic acid, anepihalohydrin, and an alkyl-modified fatty acid containing a tertiaryamine are reacted to generate the cationic surfactant. FIG. 6 shows anexample flow chart of a reaction scheme 600 for a one-step synthesis ofcationic surfactants. At 602, a modified fatty acid that contains atertiary amine is combined in solution with a carboxylic acid in a 1:1molar ratio. At 604, the mixture is refluxed for 0.5-2 hours. At 606, anepihalohydrin is added to the mixture, in a 1:1:1 ratio with themodified fatty acid and carboxylic acid. At 608, the mixture is stirredwith heating for 5-24 hours. At 610, the solvent is removed. At 612, theproduct is recrystallized. At 614, the final product, the cationicsurfactant, is obtained by filtering. FIG. 7 shows an example reactionof the one-step process 600, whereN,N-dimethylerucyl-1,3,-propylenediamine is combined with a carboxylicacid and epichlorohydrin to yield the cationic surfactant. Suitablecarboxylic acids include, but are not limited to, acetic acid (R═—CH₃),trifluoroacetic acid (R═—CF₃), and propionic acid (R═−CH₂−CH₃).

EXAMPLES

Tables 1 and 2 summarize the reactants for the one- and two-stepsynthetic processes, described in more detail below.

TABLE 1 Summary of One-Step Processes, Examples 1, 3, 5, and 7 Example 13 5 7 modified N,N-dimethyl- N,N-dimethyl- N,N-dimethyl- N,N-dimethyl-fatty acid erucyl-1,3- erucyl-1,3- erucyl-1,3- erucyl-1,3-propylenediamine propylenediamine propylenediamine propylenediamineepoxide epichlorohydrin epichlorohydrin epichlorohydrin epichlorohydrincarboxylic none - base to open acetic acid trifluoroacetic acidpropionic acid acid epichlorohydrin ring

TABLE 2 Summary of Two-Step Processes, Examples 2, 4, and 6 Example 2 46 carboxylic acetic acid trifluoroacetic acid propionic acid acidepoxide epichlorohydrin epichlorohydrin epichlorohydrin catalyst TBABTBAB TBAB fatty acid N,N-dimethyl- N,N-dimethyl- N,N-dimethyl-erucyl-1,3- erucyl-1,3- erucyl-1,3- propylenediamine propylenediaminepropylenediamine

Example 1 Synthesis of Dihydroxyl Group: Erucyl Amidopropyl-2,3-Dihydroxypropyl Ammonium Chloride (C₂₂APDAC)

50 mmol of N, N-dimethyl-erucyl-1, 3-propylenediamine and 55 mmol ofepichlorohydrin were dissolved in 30 mL of ethanol. The mixture wasstirred at 65° C. for 7 hours. Next, 50 mmol of NaOH was added to themixture by adding 6.67 ml of 30 wt % NaOH solution, and the mixture wascontinuously stirred for 3 hours. After 3 hours, the ethanol solvent wasremoved under reduced pressure. The synthesized product wasrecrystallized in acetone and refrigerated at −15° C. for 48 hours.Following refrigeration, a light yellow paste was obtained by filtering.The yield of erucyl amidopropyl-2-hydroxy-3-acetoxypropyl ammoniumchloride (C₂₂APDAC) was 76.1% by weight.

FIG. 8 shows an example infrared (IR) spectrum of C₂₂APDAC, confirmingthe structure of C₂₂APDAC as synthesized in Example 1. The wideabsorption at 3290 cm⁻¹ is due to the —N—H stretching vibration and the—O—H stretching vibration. The peaks at 2921 cm⁻¹ and 2857 cm⁻¹ are thestretching vibrations of the —CH₃ and —C—H—(—CH₂—) groups, respectively.The peak at 1651 cm^(—1) is the —C═O stretching vibration of the amidegroup. The peak at 716 cm⁻¹ indicates the existence of the alkyl chain.Accordingly, the IR spectrum in FIG. 8 confirms the structure ofC₂₂APDAC.

FIG. 9 is an example ¹HNMR spectrum of C₂₂APDAC, confirming thestructure of C₂₂APDAC as synthesized in Example 1. C₂₂APDAC was analyzedat 400 MHz in deuterated methanol. The following spectral peaks wereobserved, wherein s is a singlet, t is a triple, and m is a multiplet:0.91 (m, 3H, 1), 1.31 (s, 30H, 2),1.62 (s, 2H, 3), 2.05 (m, 6H, 4), 2.21(m, 2H, 5), 3.30 (m, 14H, 6), 4.25 (m, H, 7), 5.35 (t, 2H, 8). The ¹HNMRspectrum provides additional confirmation of the structure of C₂₂APDAc.

Example 2 Two-Step Synthesis of ErucylAmidopropyl-2-Hydroxy-3-Acetoxypropyl Ammonium Chloride (C₂₂APHAAC)

250 mmol of acetic acid, 200 mmol of epichlorohydrin, and 6.25 mmol oftetrabutylammonium bromide (TBAB) were combined. The reaction mixturewas heated to 90° C. with stirring for 10 hours. After the reaction, themixture was washed with saturated NaCl solution until the pH of themixture was around 7. The remaining water in the mixture was removedusing Na₂SO₄. The product was recovered by filtering the solid. Theyield of 3-chloro-2-hydroxypropyl acetate was about 65% by weight.

25 mmol of N, N-dimethyl-erucyl-1, 3-propylenediamine and 30 mmol of3-chloro-2-hydroxypropyl alkyl ester were dissolved in 30 mL ethanol.The mixture was refluxed at 65° C. for 10 hours. The solvent was thenremoved under reduced pressure using a rotary evaporator. Thesynthesized product was recrystallized with acetone and refrigerated at−15° C. for 48 hours. Following refrigeration, a light yellow paste wasobtained by filtering the solution. The yield of the ester cationicsurfactant erucyl amidopropyl-2-hydroxy-3-acetoxypropyl ammoniumchloride (C₂₂APHAAC) was 82.5% by weight.

Example 3 One-Step Synthesis of ErucylAmidopropyl-2-Hydroxy-3-Acetoxypropyl Ammonium Chloride (C₂₂APHAAC)

50 mmol of N, N-dimethyl-erucyl-1, 3-propylenediamine was mixed with 50mmol of acetic acid in 10 mL of isopropanol. The mixture was heated to95° C. for 0.5 hours. 60 mmol of epichlorohydrin was added to themixture. The mixture was then refluxed at 95° C. for 7 hours. Thesolvent was removed under reduced pressure to yield a yellow, oilyproduct. The synthesized product was recrystallized with acetone at −15°C. for 24 hours. The purified product was obtained by filtering. Theyield of the ester cationic surfactant C₂₂APHAAC was 84.85% by weight.

FIG. 10 shows an example IR spectrum of C₂₂APHAAC, confirming thestructure of C₂₂APHAAC as synthesized in Example 3. The wide absorptionat 3290 cm⁻¹ is due to the N—H stretching vibration and the —O—Hstretching vibration. The peaks at 2927 cm⁻¹ and 2850 cm⁻¹ areconsidered to be the stretching vibration of —CH₃ and —C—H—(CH₂—)groups. The peak at 1744 cm⁻¹ is considered to be the —C═O stretchingvibration of the ester group and the peak at 1651 cm⁻¹ is considered tobe the −C═O stretching vibration of the amide group. The peak at 726cm⁻¹ indicates the existence of the alkyl chain. Accordingly, the IRspectrum confirms the structure of C₂₂APHAAC as synthesized in Example3.

FIG. 11 shows an example ¹HNMR spectrum of C₂₂APHAAC, confirming thestructure of C₂₂APHAAC as synthesized in Example 3. C₂₂APHAAC wasanalyzed at 400 MHz in deuterated methanol. The following spectral peakswere observed, wherein s is a singlet, t is a triple, and m is amultiplet: 0.91 (m, 3H, 1), 1.31 (s, 30H, 2),1.62 (s, 2H, 3), 2.05 (m,5H, 4), 2.22 (m, 2H, 5), 2.90 (m, 3H, 6), 3.32 (m, 14H, 7), 4.09 (t, 1H,8), 5.35 (t, 2H, 9). The ¹HNMR spectrum provides additional confirmationof the structure of C₂₂APHAAC.

Example 4 Two-Step Synthesis of Erucyl Amidopropyl-2-Hydroxy-3-(2,2,2Trifluoroacetoxy) Propyl Ammonium Chloride (C₂₂APHFAC)

C₂₂APHFAC was prepared with the same two-step method as Example 2,except with trifluoroacetic acid instead of acetic acid. 250 mmol oftrifluoroacetic acid, 200 mmol of epichlorohydrin, and 6.25 mmol oftetrabutylammonium bromide (TBAB) were combined. The reaction mixturewas heated to 90° C. with stirring for 10 hours. After the reaction, themixture was washed with saturated NaCl solution until the pH of themixture was around 7. The remaining water in the mixture was removedusing Na₂SO₄. The product was recovered by filtering the solid. Theyield of 3-chloro-2-hydroxypropyl 2, 2, 2-trifluoroacetate was 70% byweight.

25 mmol of N, N-dimethyl-erucyl-1,3-propylenediamine and 30 mmol of3-chloro-2-hydroxypropyl 2,2,2-trifluoroacetate were dissolved in 30 mLethanol. The mixture was refluxed at 65° C. for 10 hours. The solventwas then removed under reduced pressure. The synthesized product wasrecrystallized with acetone and refrigerated at −15° C. for 48 hours. Alight yellow paste was obtained by filtering the solution. The yield ofthe ester cationic surfactant C₂₂APHFAC was 82.5%.

Example 5 One-Step Synthesis of ErucylAmidopropyl-2-Hydroxy-3-(2,2,2-Trifluoroacetoxy) Propyl AmmoniumChloride (C₂₂APHFAC)

C₂₂APHFAC was prepared by a one-step method with the same procedures asExample 3, except trifluoroacetic acid was used instead of acetic acid.50 mmol of N, N-dimethyl-erucyl-1, 3-propylenediamine was mixed with 50mmol of trifluoroacetic acid in 10 mL of isopropanol. The mixture washeated to 95° C. for 0.5 hours. 60 mmol of epichlorohydrin was added tothe mixture. The mixture was then refluxed at 95° C. for 7 hours. Thesolvent was removed under reduced pressure. The synthesized product wasrecrystallized with acetone at -15° C. for 24 hours. The purifiedproduct was obtained by filtering. The yield of the ester cationicsurfactant C₂₂APFAC was 70% by weight.

FIG. 12 shows an example IR spectrum of C₂₂APFAC, as synthesized inExample 5. The IR spectrum shows a wide absorption at 3348 cm⁻¹ due tothe —N—H stretching vibration and the —O—H stretching vibration. Thepeaks at 2919 cm⁻¹ and 2845 cm⁻¹ are considered to be the stretchingvibrations of —CH₃ and —C—H (—CH₂—) groups. The peak at 1682 cm⁻¹ isconsidered to be the —C═O stretching vibration of the ester group andthe peak at 1652 cm⁻¹ is considered to be the —C═O stretching of theamide group. The peak at 726 cm⁻¹ indicates the existence of the alkylchain. Accordingly, the IR spectrum confirms the structure of C₂₂APFAC.

FIG. 13 shows an example ¹HNMR spectrum, confirming the structure ofC₂₂APFAC as synthesized in Example 5. C₂₂APFAC was analyzed at 400 MHzin deuterated methanol. The following spectral peaks were observed,wherein s is a singlet, t is a triple, and m is a multiplet: 0.90 (m,3H, 1), 1.31 (s, 30H, 2), 1.63 (s, 2H, 3), 2.05 (m, 7H, 4), 3.21 (m,14H, 5), 4.09 (t, 1H, 6), 5.36 (t, 2H, 7). The ¹HNMR spectrum providesadditional confirmation of the structure of C₂₂APFAC.

Example 6 Two-Step Synthesis of ErucylAmidopropyl-2-Hydroxy-3-Propoionyloxy Propyl Ammonium Chloride(C₂₂APHPAC)

C₂₂APHPAC was prepared by a two-step method with the same procedures asexample 2, except using propionic acid instead of acetic acid. 250 mmolof propionic acid, 200 mmol of epichlorohydrin, and 6.25 mmol oftetrabutylammonium bromide (TBAB) were combined. The reaction mixturewas heated to 90° C. with stirring for 10 hours. After the reaction, themixture was washed with saturated NaCl solution until the pH of themixture was around 7. The remaining water in the mixture was removedusing Na₂SO₄.

The product was recovered by filtering the solid. The yield of3-chloro-2-hydroxypropyl propionate was 50% by weight.

25 mmol of N, N-dimethyl-erucyl-1, 3-propylenediamine and 30 mmol of3-chloro-2-hydroxypropyl propionate were dissolved in 30 mL ethanol. Themixture was refluxed at 65° C. for 10 hours. The solvent was thenremoved under reduced pressure. The synthesized product wasrecrystallized with acetone and refrigerated at −15° C. for 48 hours.The product was obtained by filtering the solution. The yield ofC₂₂APHPAC was 53%.

Example 7 One-Step Synthesis of ErucylAmidopropyl-2-Hydroxy-3-Propionyloxy Propyl Ammonium Chloride(C₂₂APHPAC)

C₂₂APHPAC was prepared by a one-step method with the same procedures asExample 3, except that propionic acid was used in place of acetic acid.50 mmol of N, N-dimethyl-erucyl-1, 3-propylenediamine was mixed with 50mmol of propionic acid in 10 mL of isopropanol. The mixture was heatedto 95° C. for 0.5 hours. 60 mmol of epichlorohydrin was added to themixture. The mixture was then refluxed at 95° C. for 7 hours. Thesolvent was removed under reduced pressure. The synthesized product wasrecrystallized with acetone at −15° C. for 24 hours. The purifiedproduct was obtained by filtering. The yield of the cationic surfactantC₂₂APHPAC was 54%.

FIG. 14 shows an example IR spectrum of C₂₂APHPAC as synthesized inExample 7. The wide absorption at 3317 cm⁻¹ is due to the —N—Hstretching vibration and the —O—H stretching vibration. The peaks at2917 cm⁻¹ and 2835 cm⁻¹ are considered to be the stretching vibrationsof the —CH₃ and —C—H— (—CH₂—) groups, respectively. The peak at 1680cm⁻¹ is considered to be the —C═O stretching vibration of the estergroup, and the peak at 1617 cm⁻¹ is considered to be the —C═O stretchingvibration of the amide group. The peak at 716 cm⁻¹ indicates theexistence of the alkyl chain. Accordingly, the IR spectrum confirms thestructure of C₂₂APHPAC.

FIG. 15 shows an example ¹HNMR spectrum, confirming the structure ofC₂₂APHPAC as synthesized in Example 7. C₂₂APHPAC was analyzed at 400 MHzin deuterated methanol. The following spectral peaks were observed,wherein s is a singlet, t is triple, and m is multiplet: 0.91 (m, 3H,1), 1.31 (s, 33H, 2),1.62 (s, 2H, 3), 2.05 (m, 7H, 4), 2.23 (m, 2H, 5),3.27 (m, 10H, 6), 3.52 (m, 4H, 7), 4.41 (t, 1H, 8), 5.36 (t, 2H, 9). The¹HNMR spectrum provides additional confirmation of the structure ofC₂₂APHPAC.

Example 8 Properties of Product Surfactants

The properties of the surfactants in seawater including compatibility,critical micelle concentration (CMC) and the interfacial tension wereinvestigated. The composition of seawater is listed in Table 3 and theobserved properties of the surfactants are presented in Table 4.

TABLE 3 Chemical composition of seawater Cations Anions Total SeawaterNa⁺ Ca²⁺ Mg²⁺ Cl⁻ HCO₃ ⁻ SO₄ ²⁻ salinity Concen- 18,300 659 2,110 32,200120 4,290 57,670 tration (ppm)

TABLE 4 Properties of surfactants Compatibility¹ CMC IFT (mN/m)Surfactant 25° C. 95° C. (mol/L) 500 mg/L 1000 mg/L 2000 mg/L C₂₂APDAC AA 9.58 × 10⁻⁶ 2.11 × 10⁻⁴ 1.21 × 10⁻⁴  1.1 × 10⁻³ C₂₂APHAAC A B 1.09 ×10⁻⁵ 1.11 4.83 × 10⁻³ 2.37 × 10⁻³ C₂₂APHFAC A B 1.08 × 10⁻⁵ 0.31 1.87 ×10⁻² 7.12 × 10⁻³ C₂₂APHPAC A B 1.25 × 10⁻⁵  5.7 × 10⁻²   7 × 10⁻³  4.2 ×10⁻² ¹A = clear; B = phase separation.

As shown in Table 4, the cationic surfactants synthesized in thisdisclosure have low interfacial tension and are soluble in high salinityenvironments. Low CMC values indicate the applicability of thesurfactant at low concentrations. Accordingly, these solvents will beuseful in a number of applications, including enhanced oil recovery.

The following units of measure have been mentioned in this disclosure:

Unit of Measure Full form L liter mL milliliter mg milligram mmolmillimole mN milli Newtons m meter ppm parts per million ° C. degreeCelsius hr hour cm⁻¹ inverse centimeter, wavenumber MHz megahertz

In some implementations, a composition includes a compound of Formula I:

where X is halide, R₁ is a saturated or unsaturated alkyl with 4 to 28carbons, R₂ is alkyl, R₃ is methyl, and R₄ is selected from the groupconsisting of

This aspect, taken alone or combinable with any other aspect, caninclude the following features. R₂ is propyl.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. R₁ is a monounsaturated alkyl chain with21 carbons.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. R₁ is

This aspect, taken alone or combinable with any other aspect, caninclude the following features. R₄ is

This aspect, taken alone or combinable with any other aspect, caninclude the following features. R₄ is

This aspect, taken alone or combinable with any other aspect, caninclude the following features. R₄ is

In some implementations, a composition includes a compound of FormulaII:

where R is selected from the group consisting of:

and where X is halide.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. R is

This aspect, taken alone or combinable with any other aspect, caninclude the following features. R is

This aspect, taken alone or combinable with any other aspect, caninclude the following features. R is

In some implementations, a process includes reacting a fatty acidmodified with an amino alkyl group and an epihalohydrin, the presence ofa base, to afford a cationic surfactant.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting the fatty acid modified with anamino alkyl group includes reacting N,N-dimetyl-erucyl-1,3,-propylenediamine.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting the epihalohydrin includesreacting epichlorohydrin.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting in the presence of a baseincludes reacting in a presence of sodium hydroxide.

In some implementations, a process includes reacting a fatty acidmodified with an amino alkyl group, an epihalohydrin, and a carboxylicacid to afford a cationic surfactant.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a fatty acid modified with anamino alkyl group includes reacting N,N-dimethyl-erucyl-1, 3,-propylenediamine.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting an epihalohydrin includesreacting epichlorohydrin.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a carboxylic acid includesreacting a carboxylic acid selected from acetic acid, propionic acid;and trifluoroacetic acid.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a carboxylic acid includesreacting acetic acid.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a carboxylic acid includesreacting propionic acid.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a carboxylic acid includesreacting trifluoroacetic acid.

In some implementations, a process includes reacting a carboxylic acid,an epihalohydrin, and a catalyst to afford a halo-substituted alkylester. The process includes reacting the halo-substituted alkyl esterwith a fatty acid modified with an amino alkyl group to afford acationic surfactant.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a catalyst includes reactingtetrabutylammonium bromide.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting an epihalohydrin includesreacting epichlorohydrin.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a carboxylic acid includesreacting a carboxylic acid selected from acetic acid, propionic acid,and trifluoroacetic acid.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a carboxylic acid includesreacting acetic acid.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a carboxylic acid includesreacting propionic acid.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a carboxylic acid includesreacting trifluoroacetic acid.

This aspect, taken alone or combinable with any other aspect, caninclude the following features. Reacting a fatty acid modified with anamino alkyl group includes reacting N,N-dimetyl-erucyl-1,3,-propylenediamine.

The term “about” as used in this disclosure can allow for a degree ofvariability in a value or range, for example, within 10%, within 5%, orwithin 1% of a stated value or of a stated limit of a range.

The term “substantially” as used in this disclosure refers to a majorityof, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%,97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more.

The term “alkyl,” employed alone or in combination with other terms,refers to a saturate hydrocarbon group that may be straight-chain orbranched.

The terms “halo” or “halogen,” used alone or in combination with otherterms, refers to fluoro, chloro, bromo, and iodo.

The term “solvent” as used in this disclosure refers to a liquid thatcan dissolve a solid, another liquid, or a gas to form a solution.Non-limiting examples of solvents are silicones, organic compounds,water, alcohols, ionic liquids, and supercritical fluids.

As used in this disclosure, “weight percent” (wt %) can be considered amass fraction or a mass ratio of a substance to the total mixture orcomposition. Weight percent can be a weight-to-weight ratio ormass-to-mass ratio, unless indicated otherwise.

A number of implementations of the disclosure have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the disclosure.

What is claimed is:
 1. A process comprising reacting: a fatty acidmodified with an amino alkyl group; and an epihalohydrin, in a presenceof a base, to afford a cationic surfactant.
 2. The process of claim 1,wherein reacting the fatty acid modified with an amino alkyl groupcomprises reacting N, N-dimetyl-erucyl-1,3,-propylenediamine.
 3. Theprocess of claim 1, wherein reacting the epihalohydrin comprisesreacting epichlorohydrin.
 4. The process of claim 1, wherein reacting inthe presence of a base comprises reacting in a presence of sodiumhydroxide.